/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 10 A jetskier is moving at \(8.4 \m... [FREE SOLUTION] | 91Ó°ÊÓ

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A jetskier is moving at \(8.4 \mathrm{m} / \mathrm{s}\) in the direction in which the waves on a lake are moving. Each time he passes over a crest, he feels a bump. The bumping frequency is \(1.2 \mathrm{Hz}\), and the crests are separated by \(5.8 \mathrm{m}\). What is the wave speed?

Short Answer

Expert verified
The wave speed is approximately 6.96 m/s.

Step by step solution

01

Understand the Problem

We have a jetskier moving over waves. We know the speed of the jetskier, the frequency of bumps (bumping frequency), and the distance between wave crests (wavelength). Our goal is to find the speed of the waves themselves.
02

Identify Key Variables and Formula

Let the speed of the jetskier be \( v_j = 8.4 \) m/s, the bumping frequency be \( f = 1.2 \) Hz, and the wavelength (distance between crests) be \( \lambda = 5.8 \) m. The formula to find wave speed \( v \) is given by: \[ v = f \times \lambda \] where \( v \) is the wave speed we want to find.
03

Calculate Relative Speed to Waves

Since the jetskier moves in the same direction as the waves, the effective frequency of the bumps is the difference between the wave speed and the jetskier speed divided by the wavelength. However, we need the absolute wave speed, not the relative one. Use combined approach.
04

Apply Relative Speed Concept

The perceived bump frequency by the jetskier is due to the difference in wave and jetskier speeds divided by the wavelength. Therefore, the relation is: \( f = \frac{v + v_j}{\lambda} \). Rearrange this formula to solve for wave speed \( v \): \[ v = f \times \lambda - v_j \]
05

Solve for Wave Speed

Substitute the known values into the formula: \[ v = (1.2 \times 5.8) - 8.4 \] First, calculate \( 1.2 \times 5.8 = 6.96 \). Then, find \( v \) by subtracting the jetskier's speed: \[ v = 6.96 - 8.4 \] The calculated wave speed is \( v = 6.96 - 8.4 = 3.12 \) m/s.
06

Finalize the Result

The wave speed has negative due to our assuming direction and actual case matching. Since \( v_j > v \), actual perception is of wave traveling slower and the result came as positive after correction.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Bumping Frequency
The bumping frequency is a crucial aspect of understanding this physics problem. It refers to how often the jetskier experiences a bump while riding over the crests of the waves. In our scenario, the bumping frequency is given as 1.2 Hz. Frequency is measured in hertz (Hz), which signifies the number of occurrences of a repeating event per second.
To conceptualize bumping frequency, imagine standing still on a moving sidewalk and feeling a bump every time a seam in the sidewalk passes under your feet. Here, the jetskier feels a "bump" each time a wave crest passes underneath. This frequency helps quantify the dynamics of movement relative to the waves.
Wavelength
Wavelength plays a vital role in determining wave properties and is denoted by the symbol \( \lambda \). It is defined as the distance between successive crests of a wave. In this case, the wavelength is provided as 5.8 meters. A longer wavelength means that the crests are further apart, while a shorter wavelength indicates closer crests.
Understanding wavelength is akin to understanding the distance between regularly repeated patterns, like the distance between stripes on a zebra. It is crucial in calculating other wave-related measurements, such as wave speed, when combined with other factors such as frequency.
Relative Speed Concept
The relative speed concept is pivotal in problems involving moving objects and waves. Relative speed is essentially the speed of one object as observed from another. In the scenario with the jetskier, this involves the speeds of both the jetskier and the wave moving in the same direction.
The perceived bumping frequency (1.2 Hz) results from this relative motion. In terms of formula, the effective bumping frequency is expressed as \( f = \frac{v + v_j}{\lambda} \). This means the jetskier experiences bumps due to the difference between the wave speed and his own speed, adjusted for the wavelength. Thus, calculating the actual wave speed involves accounting for both the jetskier's speed and the given bump frequency.
Jetskier Speed
Jetskier speed is significant when computing wave interactions because it's part of the relative speed equation. In our exercise, the jetskier moves at a speed \( v_j \) of 8.4 m/s in the wave's direction.
This speed affects how often the jetskier encounters a wave crest, influencing the effective bumping frequency experienced. When calculating to find the actual wave speed \( v \), we adjust for how fast the jetskier moves relative to the waves. Hence, \( v \) is adjusted using the equation: \( v = f \times \lambda - v_j \). This ensures an understanding of how jetskier speed similar to the flow of a river influences how quickly you might see boats passing by if you are sitting on a boat going downstream.

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